ryanrlamothe
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Engine Management - 2006/04/05 18:29
This thread is in continuation of the technical portions of this thread.
Improper engine management is the #1 reason why aftermarket built and tuned engines become destroyed.
I have been meaning to ask, how do you tune your engines? At times, it sounds like you just slap on a factory ECU or an untuned stock map ECU and head out the door. Is that right? Do you have an AWD dyno nearby? How do you program your EcuTek/MoTec/etc. EM? A proper ECU tune can be the difference between good power and phenomenal power, between unreliable and unbreakable.
On further review, a reprogrammed ECU might be needed in your CR build in order for the engine to properly prevent detonation. The factory ECU will be unaware of the change in CR, and there are some interesting changes with the new pistons as well including a change in quench area and dish design. I would think that the change in CR is going to change your fuel ignition point with a corresponding increase in your combustion temperature. A tighter quench area should work to increase thermal efficiency, cooling the combustion slightly, allowing slightly higher CR's, but will it be enough to allow 11.2:1 CR pistons with an ECU designed to run 10:1 CR or lower? If nothing else, I would assume a change in A/F ratio to a much richer mixture would be required, at the very least, to cool the cylinder walls and pistons in an effort to avoid predetonation. I would also watch the EGT's to make sure you are not running anything way too lean/hot.
These are just some of my thoughts on the conversation, do you have any other comments/corrections/etc.?
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Matt
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Re:Engine Management - 2006/04/05 19:31
So far we haven't have an opportunity to bring a car to the dyno. We're using exclusivly autronic ECUs. The maps we have right now are bench tuned from the distributer. They are tuned very conservitavly. There is a ton of gains that we could realize from a real tuning session.
At Oregon trail last year we had a very nice prodrive tuner help us with Kylie's Pectel ECU. It wasn't a tuning, but he knocked a few settings around and got us a little more power.
I'm planning on taking Both Eve and Deepii to a dyno to get more preformance out of them.
Most tuners don't need a dyno, They will typically tune a car just driving down the street, or alternativly, listen for knock, tune untill they get knock, and then back it doen from there. Obviously these tuning methods arn't nearly as scientific as dyno time. The dyno gives real numbers, not just "It feels good". Somepeople say that the Dyno doeesn't simulate real world conditions. while that may be true for some, most dyno's can simulate load conditions.
With my high compression street car project, is just can't be bothered to do the job right  A factory ECU has a lot more working sensors than your typical rally car. While very well built cars will have Map, Air temp, charge temp, exhaust temp, and knock sensors, most cars have only map or mass air. Antilag exhaust temps have a tendency of destroying sensors. Also, unless the knock sensor is made to only detect during a certain time window, it will be fooled by the many knocking sounds that happen in rally conditions. Sensor choices are prepretty limited. Where was I?
My street car atleast has the benifit of map, knock and O2 sensors. question on my mind is can a stock ecu deal with the change? Is shouldn't be impossible to get a real tuning if when I start the motor it causes a ruckus.
Additionally, ther emust be someone who has done this exact thing and has map for it, which I could flash in. I just have to find them.
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ryanrlamothe
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Re:Engine Management - 2006/04/06 16:37
Matthew Wallace Iorio wrote:
Most tuners don't need a dyno, They will typically tune a car just driving down the street, or alternativly, listen for knock, tune untill they get knock, and then back it doen from there. Obviously these tuning methods arn't nearly as scientific as dyno time. The dyno gives real numbers, not just "It feels good". Somepeople say that the Dyno doeesn't simulate real world conditions. while that may be true for some, most dyno's can simulate load conditions.
More like most tuners do not have a dyno, as opposed to not needing a dyno, therefore they cannot use one to do proper tuning. While some people say dynos don't give real world numbers, I just laugh. Honestly, an engine is a heat pump that converts chemical energy into mechanical energy, it is as scientific as it gets for this system. While a "road tune" may appear more accurate to some, it is more likely because the "dyno tune" was done incorrectly, is lacking proper A/F corrections, or the EMS is not physically compensating properly for current conditions. Modern EMS's have built-in altimeters, accelerameters, humidistats, automatic timing retard/advance, etc. so with a proper tune those factors shouldn't even be an issue. Usually, it is a matter of a change in mechanical components between dyno tunes, even a minor change in mechanical components can make a huge difference in engine performance. Which just leads back to my first point, the people doing the road tune simply do not have access to a dyno for proper tuning, so road tuning is all they can do.
Could you imagine ProDrive or Ralliart saying "Screw this bloody dyno, I'm going out to road tune this engine". LOL. Of course, I could see that excuse being used at times, given some of the amazing roads in places like Scotland, Germany, etc. 
A dyno tunes are also used in combination with road tests to make sure the entire package performs the way it is intended.
Here is a link to MRT's Dyno and the blue box on the top of Page 2 lists some important points as well.
With my high compression street car project, is just can't be bothered to do the job right A factory ECU has a lot more working sensors than your typical rally car. While very well built cars will have Map, Air temp, charge temp, exhaust temp, and knock sensors, most cars have only map or mass air. Antilag exhaust temps have a tendency of destroying sensors. Also, unless the knock sensor is made to only detect during a certain time window, it will be fooled by the many knocking sounds that happen in rally conditions. Sensor choices are prepretty limited. Where was I?
My street car atleast has the benifit of map, knock and O2 sensors. question on my mind is can a stock ecu deal with the change? Is shouldn't be impossible to get a real tuning if when I start the motor it causes a ruckus.
Additionally, ther emust be someone who has done this exact thing and has map for it, which I could flash in. I just have to find them.
Interesting about the Rally car components, it makes sense that everything from the exhaust manifold back would get toasted pretty quickly with anti-lag. Although aren't there systems built to withstand that kind of use? The EMS's systems I have seen have some pretty incredible sensoring abilities, including complete data logging for future tuning and mechanical tweaking.
Autronic does make some very nice EMS's. There are also systems by MoTec, HalTech, EcuTek, PossumLink, Link, and others. What made you decide on Autronic?
As for your street build, you could also go with a "piggy-back" solution to help your A/F ratios a bit with the higher CR. While a piggy-back solution is far from ideal when used with Subaru ECU's, a system from Unichip, Perfect Power, U-Tec, or others could easily fit your needs for a fairly reasonable price. You can get Perfect Power here in the US from RalliTek as well as other places.
Post edited by: ryanrlamothe, at: 2006/04/06 16:51
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ryanrlamothe
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Re:Engine Management - 2006/04/06 17:06
Also, with your Subaru 2.5L NA build, what cams are you looking at using? The stock cams are not very hot, but a nice set of these or these would be great. I would think that with the second link you would also want to upgrade the valetrain components as well, since your current valvetrain setup is pretty much limited to ~6500RPM or so for redline without getting into valve float problems at higher RPM's.
Yes, a set of high CR pistons, club racing cams, high lift valvetrain, and Perfect Power piggyback ECU could make for some nice performance. You also cannot make power unless your engine is breathing properly. At that point, I would also consider a nice, properly designed CAI and exhaust. For an NA solution, a good true equal length header design would work great, like this one. I would also probably be looking into a nice port and polish and possibly even a 3-way valve job. With that kind of work, you could push the 2.5L NA into the +200BHP area without too much of a problem.
Interestingly, you could also put a 3.0L H6 into your GC8 Impreza as well and have all of the power without any of the engine work. Anders Green did this with his GC8 Impreza and has Rallied it successfully a couple of times already. Here is the link.
Post edited by: ryanrlamothe, at: 2006/04/06 17:10
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RalliSpec
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Re:Engine Management - 2006/05/01 21:30
I was just scoping out your site. Interesting technical dicussions you have going on here.
Just thought I would give you a little insight....
AWD dynos cost upwards of $100,000. This is the main reason why many tuners don't have one. That includes us. Even if we had the money we have no space.
Every car that is tuned on a dyno should be road tested in order to evaluate the results in real world conditions. The conditions on the dyno are not 100% realistic. The way the wheels are loaded and the airflow through the engine bay and intercooler are not be totally representative. Just assuming that its going to be fine out on the road is a big mistake. Vishnu Tuning does a lot of EcuTek dyno tune sessions with big groups of people where he bangs out these cars in 15 minutes and sends people on their way never actually road testing. I can't keep track of how many cars we've had to retune to correct major driveability and boost curve issues. What sucks is Vishnu probably made more money doing it wrong the first time in 15 minutes then we make retuning it over the course or an hour or two.
Subaru WRX/STi factory ECU's can be road tuned quite well because the ECU's have very sophisticated adaptive ignition timing systems. Basically if you get the ECU in the ball park and give it a little headroom it will literally advance itself up the knock point for maximum power. And if you get the shape of the "advance curve" wrong you can use the software to see exactly where the ECU is pulling timing or increasing timing and reshape it. That combined with a fairly accurate dyno simulation program allows an experienced tuner to achieve results 99% as good as with a dyno. The only time that is not the case is when you stray quite far from the stock setup....like extreme internal modifications, massive turbos, etc. And even then its more about time spent than anything else....you could spend days road tuning an extreme setup to get it right whereas it could be tuned in a few hours on a dyno.
Stand alone systems are a different story. Stand alones generally do not have very sophisticated knock control or adaptive ignition timing. If you don't tell it the right air-fuel ratio and amount of timing advance at every load and rpm point then your engine will quite possibly go boom real quick. So most of the time with a road tune you have to be super conservative or spend a whole lot of time on the car (usually attracting attention of local law enforcement). Some of the more expensive stand alones are getting more sophisticated...but still a long way off of what the factory ECU's are doing.
--Dave
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